1-3 composites for ultrasonic air transducers

The coupling of ultrasound into air from piezoelectrics is very inefficient because of the great impedance mismatch and the lack of appropriate matching materials. A method to manufacture low impedance materials using 1-3 air composites is presented. This technique also requires the development of an alternative matching technique using a low impedance lambda /8 section and a thin cap. It is shown that this technique works almost as well as standard lambda /4 matching. A transducer is fabricated using this design technique with a one-way loss of 17 dB.< >